Gasoline mixed with oil for two strokes is less flammable than "pure" gasoline. How much less I don't know. Maybe someone does? Anyway, is this taken into consideration when banning gasoline engines at your field? Maybe the "corrupted" by ethanol gasolne is less flammable? Does anyone know?

You could install a fire suppression system on your airplane, or you could guarantee you won't crash and burn.

Turbines fueled with kerosene also burn, we had one "land" in a tree and it just burned and burned to a nice char as we looked on[]

Maybe arrange to have a local fire truck standby while you fly your gassers.

Of course, if the Japan disaster continues, the farmers crops will all be radioactive and worthless anyway.

Good luck